What are common pitfalls or gotchas with regex best practices?

When working with regular expressions in Perl, there are several common pitfalls and gotchas that developers should be aware of to write efficient and effective regex patterns. Here are some best practices to keep in mind:

1. Greediness vs. Laziness: By default, quantifiers are greedy, meaning they match as much text as possible. Be mindful of using non-greedy quantifiers (e.g., *? or +?) when necessary to avoid unexpected matches.

2. Escaping Special Characters: Many characters in regex have special meanings (e.g., ., *, ?, +). Remember to escape these characters using a backslash (\) if you want to treat them as literal characters.

3. Using Anchors Wisely: Anchors (like ^ for the start of a string and $ for the end) should be used properly to ensure you are matching the entire string as intended, rather than allowing unwanted matches within a larger string.

4. Overusing Capture Groups: Utilize capture groups when needed, but avoid overuse as they may lead to performance issues. Use non-capturing groups (?:...) when you only need to group without capturing.

5. Performance Considerations: Regex can be slow with particularly complex patterns or large input. Always test regex patterns against the expected size of the input data.